1. Field
The disclosure relates to amplifier design, and more particularly, to techniques for designing a variable gain instrumentation amplifier.
2. Background
In the design and testing of integrated circuits (IC's), an instrumentation amplifier may be used to buffer the output of one or more pins of an IC prior to interfacing with various laboratory test equipment. In some applications, the instrumentation amplifier may provide a preselected amplification gain to a differential voltage from two differential output pins of the IC, and also convert the amplified differential voltage into a single-ended voltage to interface with the test equipment.
When selecting from amongst a plurality of possible gain settings, it may be important for the instrumentation amplifier to avoid introducing any systematic gain offsets between gain settings. To guarantee precise gain for a plurality of gain settings, prior art techniques may resort to the use of external calibration and/or trimming. Such procedures undesirably complicate the use of the instrumentation amplifiers.
It would be desirable to provide a simple and robust instrumentation amplifier having a plurality of selectable gain settings that can provide precise gain values without the need for external calibration.